The present invention generally relates to fabrication methods and resulting structures for semiconductor devices, and more specifically, to fabrication methods and resulting structures for an area selective cyclic deposition for a vertical field effect transistor (VFET) top spacer.
Traditional metal oxide semiconductor field effect transistor (MOSFET) fabrication techniques include process flows for constructing planar field effect transistors (FETs). A planar FET includes a substrate (also referred to as a silicon slab), a gate formed over the substrate, source and drain regions formed on opposite ends of the gate, and a channel region near the surface of the substrate under the gate. The channel region electrically connects the source region to the drain region while the gate controls the current in the channel. The gate voltage controls whether the path from drain to source is an open circuit (“off”) or a resistive path (“on”).
In recent years, research has been devoted to the development of nonplanar transistor architectures. Some non-planar transistor device architectures, such as VFETs, employ semiconductor fins and side-gates that can be contacted outside the active region, resulting in increased device density and some increased performance over lateral devices. In contrast to planar FETs, the source to drain current in a VFET flows through the vertical fin in a direction that is perpendicular with respect to a horizontal major surface of the wafer or substrate. A VFET can achieve a smaller device footprint because its channel length is decoupled from the contacted gate pitch.